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  • 1
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    Rain and deicing experiments in a wind tunnel (1983)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: Comments on films of tests simulating rain and ice conditions in a wind tunnel are presented, with the aim of studying efficient methods of overcoming the adverse effects of rain and ice on aircraft. In the experiments, lifesize models and models of the Mirave 4 aircraft were used. The equipment used to simulate rain and ice is described. Different configurations of landing and takeoff under conditions of moderate or heavy rain at variable angles of incidence and of skipping and at velocities varying from 30 to 130 m/sec are reproduced in the wind tunnel. The risks of erosion of supersonic aircraft by the rain during the loitering and approach phases are discussed.
    Keywords: AERODYNAMICS
    Type: NASA-TM-77077 , NAS 1.15:77077 , May 29, 1967 - May 31, 1967; Paris
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Some characteristic quantities of Karman-Trefftz profiles (1983)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: For von Karman-Trefftz profiles, the characteristics which determine profile shape (profile nose dimensions, maximum thickness and position: tail slope and curvature) are stated as a function of transformation variables using the Timman method. The profile is obtained by iterative deformation of a von Karman profile with known transformation, corresponding as well as possible to the desired profile. The figures and relations which enable a good choice of the required profile are given.
    Keywords: AERODYNAMICS
    Type: NASA-TM-77013 , NAS 1.15:77013
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Experimental determination of the inertia constants of an airplane or of a missile (1983)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The possibility to measure the inertia constants of an airplane or of a missile by a unique experimental set up without having to materialize axes of rotation was investigated. It is sufficient to suspend the structure appropriately, to obtain the six natural modes determined by the suspension and to introduce these results as data into a computer. If the structure is very flexible it is necessary to take into account the first natural modes of deformation. Experiments on rigid and flexible models led to precise results and allow consideration of full scale measurements. The final goal is to provide, by a standard ground vibration test completed by the measured characteristics of the suspension modes, the set of data necessary for flutter calculations and for the determination of all the inertia constants.
    Keywords: AERODYNAMICS
    Type: NASA-TM-77767 , NAS 1.15:77767
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Reduction of the shock wave intensity by modifying the transonic blade trailing edge (1983)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: It is shown that the shock wave intensity can be decreased by using modified trailing edge configurations to reduce or even completely compensate for the effect of the finite thickness of the trailing edge. A theoretical analysis is presented together with numerical results for two supersonic streams flowing off the trailing edge at different velocities. The analysis is based on an ideal gas model.
    Keywords: AERODYNAMICS
    Type: NASA-TM-77029 , NAS 1.15:77029
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 5
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    Flow mechanism and experimental investigation of a rotating stall in transonic compressors (1983)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The flow characteristics of the rotating stall in compressors is studied, and a flow model is developed along with a theoretical calculation method based on vortex theory. A detailed theoretical calculation is completed for a two dimensional flow field in a transonic rotor in a rotating stall, and the result is in good agreement with experimental findings. The oscillograms of time-varying stall characteristic parameters recorded for the onset, growth, and cessation processes of rotating stall are analyzed, and some new flow phenomena deserving of further investigation are discovered. These include serious separation of individual blades, often preceding the onset of rotating stall in compressors with very small blade-camber angles, and periodical variation of the circumferential width of the stall cell with time, accompanied by periodical oscillation of the width of the stall cell in the radial direction of the blade. The circumferential and radial oscillation frequencies are the same.
    Keywords: AERODYNAMICS
    Type: NASA-TM-77373 , NAS 1.15:77373
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    Wind tunnel investigations of glider fuselages with different waistings and wing arrangements (1983)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The parameters fuselage pinch glider wing arrangement and fuselage leading edge radius of nine glider configurations were investigated in wind tunnel tests. Laminar separation bubbles were found on strongly recessed fuselages. These separations in the juncture between fuselage and wing are essential in the prevention of harmful aerodynamic drag. Drag reduction was measured with increasing pinch and the wing arrangement in the rear. These results are only valid for laminar flow on the fuselage leading edge.
    Keywords: AERODYNAMICS
    Format: application/pdf
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  • 7
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    Laminarization of a boundary layer in a supersonic nozzle by cooling of the surface (1983)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The concept of cooling of the surface of wind tunnel walls in order to laminarize the boundary layer, and thereby eliminate perturbations in the working area, is discussed. Equations are given, which are used to calculate the temperature conditions under which the flow in the boundary layer will be stably laminar.
    Keywords: AERODYNAMICS
    Type: NASA-TM-77341 , NAS 1.15:77341
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    Helicopter blade tips (1983)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: Methods of improving helicopter performance and vibration level by proper shaping of helicopter blade tips are considered. The principle involved consists of reducing the extent of the supersonic zone above the advancing tip and of the turbulent interaction. For stationary and advancing flight, the influence of the rotor and the problems posed by blade tips are reviewed. The theoretical methods of dealing with the two types of flight are briefly stated, and the experimental apparatus is described, including model triple and quadruple rotors. Different blade tip shapes are shown and briefly discussed. The theoretical results include an advancing speed of 309 km/H and a blade tip rotational speed of 215 m/s. The experimental values are advancing speed of 302 km/h and blade tip Mach number 0.86 for both types of rotors.
    Keywords: AERODYNAMICS
    Type: NASA-TM-77370 , NAS 1.15:77370 , NT-81-19 , Nov 18, 1981 - Nov 20, 1981; Poitiers; France
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 9
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    Contribution to the aerodynamic study of wings and propellers (1983)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: Various problems regarding the aerodynamics of lifting wings are solved. Two methods are proposed for replacing the wing, both involving "viscous" edge vortices. the applications give results which agree well with experiments. Two new methods are also proposed for calculating propellers based on the vortex model consisting of an edge vortex and a "viscous" hub vortex.
    Keywords: AERODYNAMICS
    Type: NASA-TM-77083 , NAS 1.15:77083
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 10
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    Computation of viscous flows over airfoils, including separation, with a coupling approach (1983)
    In:  CASI
    Details
    Publication Date: 2019-08-27
    Description: Viscous incompressible flows over single or multiple airfoils, with or without separation, were computed using an inviscid flow calculation, with modified boundary conditions, and by a method providing calculation and coupling for boundary layers and wakes, within conditions of strong viscous interaction. The inviscid flow is calculated with a method of singularities, the numerics of which were improved by using both source and vortex distributions over profiles, associated with regularity conditions for the fictitious flows inside of the airfoils. The viscous calculation estimates the difference between viscous flow and inviscid interacting flow, with a direct or inverse integral method, laminar or turbulent, with or without reverse flow. The numerical method for coupling determines iteratively the boundary conditions for the inviscid flow. For attached viscous layers regions, an underrelaxation is locally calculated to insure stability. For separated or separating regions, a special semi-inverse algorithm is used. Comparisons with experiments are presented.
    Keywords: AERODYNAMICS
    Type: NASA-TM-77079 , NAS 1.15:77079 , Computation of Viscous-Inviscid Interaction Symp.; Sep 29, 1980 - Oct 01, 1980; Colorado Springs, CO; United States
    Format: application/pdf
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